Membrane switch, method for manufacturing membrane switch, and contact switch

• US 20060042924A1
• Filed: 08/18/2005
• Published: 03/02/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Polymatech Company Limited
• Original Assignee: Polymatech Company Limited
• Inventors: Ito, Nobuhiro
• Granted Patent: US 7,186,938 B2
• Time in Patent Office: Days
• US Class Current: 200/512
• CPC Class Codes: H01H 1/027 containing carbon particles or fibres
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/79 characterised by the form of the contacts, e.g. interspersed fingers or helical networks
• CPC Class Codes: H01H 13/88 Processes specially adapted for manufacture of rectilinearly movable switches having a plurality of operating members associated with different sets of contacts, e.g. keyboards
• CPC Class Codes: H01H 2203/02 Interspersed fingers
• CPC Class Codes: H01H 2207/044 Resist layer
• CPC Class Codes: H01H 2229/004 Conductive ink
• CPC Class Codes: H01H 2239/078 Variable resistance by variable contact area or point
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 3/28 Applying non-metallic protective coatings H05K3/0091 takes precedence; methods for intermediate insulating layers for build-up multilayer circuits H05K3/4673
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A pressure detection switch includes a membrane switch and a key pad arranged on the membrane switch. The membrane switch includes first and second insulation sheets arranged to face each other. An electric circuit, which includes a first electrode and a voltage-dividing resistor, and a resist film, which protects the electric circuit, are formed on the lower surface of the first insulation sheet and above the second insulation sheet. The resist film has an opening through which the voltage-dividing resistor is exposed from the lower surface of the first insulation sheet.

Claims

1. A membrane switch comprising:

a first substrate and a second substrate arranged to face each other;

two electrodes respectively arranged on the first and second substrates in a manner that the electrodes face each other, with at least one of the electrodes being movable between a position at which the one of the electrodes comes in contact with the other one of the electrodes and a position at which the at least one of the electrodes is spaced from the other one of the electrodes;

an electric circuit arranged on the first substrate; and

a resist film, arranged on the first substrate, for protecting the electric circuit, wherein the electric circuit includes a resistive element and is formed by applying and drying conductive material, and the resist film has an opening through which the resistive element is exposed and is formed by applying and drying a resist material.

2. The membrane switch according to claim 1, wherein the resistive element is formed from a conductive material containing carbon powder.

3. The membrane switch according to claim 1, wherein the electrode arranged on the second substrate and the resistive element are formed from the same type of conductive material.

4. The membrane switch according to claim 1, wherein the electrode arranged on the first substrate includes comb-shaped teeth.

5. A contact switch comprising:

a switch body formed by a membrane switch; and

a key pad arranged on the switch body, wherein the membrane switch includes;

a first substrate and a second substrate arranged to face each other;

two electrodes respectively arranged on the first and second substrates in a manner that the electrodes face each other, wherein at least one of the electrodes is movable between a position at which the one of the electrodes comes in contact with the other one of the electrodes and a position at which the at least one of the electrodes is spaced from the other one of the electrodes, the two electrodes coming in contact with each other when pressure is applied to the key pad toward the switch body, and the two electrodes being spaced from each other when pressure is not applied to the key pad;

an electric circuit arranged on the first substrate; and

a resist film, arranged on the first substrate, for protecting the electric circuit, wherein the electric circuit includes a resistive element and is formed by applying and drying conductive material, and the resist film has an opening through which the resistive element is exposed and is formed by applying and drying a resist material.

6. The contact switch according to claim 5, wherein:

the contact switch is arranged on a circuit board;

the electric circuit includes wiring for connecting the electrode of the first substrate and the resistive element, the wiring having an end portion formed on the first substrate on a surface facing the second substrate;

the resist film has a second opening through which the end portion of the wiring is exposed;

the second substrate is arranged to face the circuit board, and the second substrate has a third opening corresponding to the end portion of the wiring; and

the key pad includes a projection, corresponding to the end portion of the wiring, for pressing the first substrate toward the circuit board through the third opening.

7. The contact switch according claim 5, wherein:

the contact switch is arranged on a circuit board;

the first substrate is arranged to face the circuit board, and the first substrate includes a surface facing the circuit board;

the electric circuit includes wiring for connecting the electrode of the first substrate and the resistive element, the wiring having an end portion formed on the surface of the first substrate facing the circuit board; and

the key pad includes a projection, corresponding to the end portion of the wiring, for pressing the first substrate toward the circuit board.

8. The contact switch according to claim 5, wherein the resistive element is formed from a conductive material containing carbon powder.

9. The contact switch according to claim 5, wherein the electrode arranged on the second substrate and the resistive element are formed from the same type of conductive material.

10. The contact switch according to claim 5, wherein the electrode arranged on the first substrate includes comb-shaped teeth.

11. A method for manufacturing a membrane switch including a first substrate and a second substrate arranged to face each other, and two electrodes respectively arranged on the first and second substrates in a manner that the electrodes face each other, wherein at least one of the electrodes is movable between a position at which the one of the electrodes comes in contact with the other one of the electrodes and a position at which the at least one of the electrodes is spaced from the other one of the electrodes, the method comprising:

applying and drying a conductive material on the first substrate to form an electric circuit having a plurality of resistive elements on the first substrate by applying the conductive material in the same direction to form each resistive element; and

applying and drying a resist material on the first substrate to form a resist film for protecting the electric circuit on the first substrate and to form in the resist film an opening through which each resistive element is exposed.

12. The method according to claim 11, wherein the electric circuit is formed by performing screen printing.

13. The method according to claim 12, wherein the electric circuit includes wiring connecting the electrode of the first substrate and each resistive element, with the direction in which the conductive material is applied to the first substrate to form each resistive element being parallel with the wiring at locations where each resistive element is arranged.

14. The method according to claim 12, further comprising:

forming the electrode on the second substrate by screen printing the electrode on the second substrate with a conductive material using a screen printing plate, wherein each resistive element of the electric circuit and the electrode formed on the second substrate are formed using the same screen printing plate.

15. The manufacturing method according claim 11, wherein the electric circuit is formed using an inkjet printing machine.